Most of us have, over the years, amassed an extensive iTunes catalog. Still, there are times when even the most deadicated audiophile looks at her mp3s and can't find the right tunes for the occasion. Rather than spending 99-cents per song for music you might not listen to again, check out these FREE resources:

2) Grooveshark - whereas Pandora plays music that is a similar sound to what you're looking for, Grooveshark lets you choose the exact artists and songs you want to listen to. If you don't have a lot of time to play around with that, pick Pandora. If you definitely want to hear songs A, B, and C - pick Grooveshark. Grooveshark also has a radio feature like Pandora, but I've found that Pandora's selections are usually more on the mark.

3) New services are popping up all the time, but some of the most popular ones include Last.fm, Deezer (here's an article comparing the two) and Spotify.